A Case Study of Development of a Java Bytecode Analyzer Framework Using AspectJ

Aspect-orientation is a new programming paradigm that can localize a cross-cutting concern in a single module. This paper proposes a new type of Java bytecode analyzer framework based on aspect-orientation. It includes several new design and implementation techniques that are general or specific to the domain of language systems. We also observe that aspect-orientation improves extensibility, type safety, execution efficiency, and simplicity of the API, when compared with existing analyzer frameworks based on object-orientation such as Soot. This paper reports the following: structural extension of elementary objects maintaining type safety and execution efficiency; separation of a bytecode parser and concrete instruction sets; a visitor based on the stack-machine model; binary operations that are simple, extensive, and easy to maintain; and separation of nonfunctional concerns such as verification. We also observe that AspectJ currently has two limitations: it is not sufficiently expressive to structure aspects strongly depending on the inner structure; and it does not provide a general approach to write advice that cannot be described with information of its pointcut only.